American physician and medical researcher, corecipient (with Baruch S. Blumberg (Blumberg, Baruch S.)) of the 1976 Nobel Prize for Physiology or Medicine for his research on the causal agents of various degenerative neurological disorders.

Gajdusek graduated from the University of Rochester (N.Y.) in 1943. He received his M.D. from Harvard University in 1946 and was a fellow in pediatrics and infectious diseases at Harvard from 1949 to 1952. In the next three years he held positions at the Institute of Research of the Walter Reed Army Medical Center in Washington, D.C., and the Institut Pasteur, Tehrān. It was in 1955, while he was a visiting investigator at the Walter and Eliza Hall Institute of Medical Research in Melbourne, Australia, that Gajdusek began the work which culminated in the Nobel Prize.

Gajdusek codiscovered and provided the first medical description of a unique central nervous system disorder occurring only among the Fore people of New Guinea and known by them as kuru (“trembling”). Living among the Fore, studying their language and culture, and performing autopsies on kuru victims, Gajdusek came to the conclusion that the disease was transmitted in the ritualistic eating of the brains of the deceased, a Fore funeral custom. Gajdusek became the head of laboratories for virological and neurological research at the National Institutes of Health (NIH) in 1958. After years of further research, much of it conducted with his NIH colleague Clarence Gibbs, Jr., he postulated that the delayed onset of the disease could be attributed to a virus capable of extremely slow action or, perhaps, having the ability to remain dormant for years.

Gajdusek's study had significant implications for research into the causes of another degenerative brain disease, called Creutzfeldt-Jakob disease. Subsequent research suggests that these diseases are caused not by viruses but rather by unusual infectious agents called prions.

In addition to his work in virology, Gajdusek was an expert in the fields of learning and behaviour, child growth and development in primitive cultures, genetics, immunology, and neurological patterning and learning.

In 1997 Gajdusek pleaded guilty to child abuse involving the sexual molestation of a teenaged boy; he served one year in prison.